We fetch to your notice a new website where you can buy propecia australia at a low cost with fast delivery to Australia.
residues), not cleaved in algae, with no equiva-
lent in conventional COXII (7
). The conserved
PxxxPxxY motif in this region of COXIIB alsoimplies a common origin for apicomplexan and
genes (fig. S1). In phyloge-netic analyses of the available COXIIA andCOXIIB sequences and representative orthodox
Soledad Funes,1 Edgar Davidson,2 Adria´n Reyes-Prieto,1
COXII sequences, apicomplexans group with
Susana Magallo´n,3 Pascal Herion,4 Michael P. King,2
chlorophytes (Fig. 1). In contrast, apicomplexan
sequences of mtDNA-encoded cytochrome bgroup independently from green algal sequences.
Apicomplexan parasites, including the hu-
predicted that this alga would also have a nuclear
The data strongly argue that apicomplexan cox2a
man pathogens Toxoplasma
) and have confirmed this (fig. S1) (9
derive from green algae, not from an
, contain a vestigial plastid, the apicoplast.
The frequency of cox2a
independently split apicomplexan cox2
. T. gon-
This chloroplast-derived organelle is the rem-
phyceae suggests an ancestral chlorophyte cox2
has an intron that is conserved in
nant of a secondary endosymbiosis between
split in the mtDNA, before independent transfers
location and phase with introns in cox2a
an ancestral apicomplexan and a photosyn-
to the nucleus. S. obliquus
sp. (figs. S1 and S2).
thetic organism whose origin is moot (1– 4
appears as an intermediate, retaining cox2a
This suggests a lateral transfer of cox2a
We have identified two distinctive apicom-
mtDNA. The incompatibility between the S.
from the green algal nucleus to the api-
plexan nuclear genes that suggest a green
mitochondrial and nuclear genetic
) may have developed after the transfer
Previous analyses have favored either a green
to the nucleus, preventing the subse-
) or a red algal (1
) apicoplast precur-
cytochrome oxidase, is usually encoded by a
sor. Because the mtDNAs of a wide variety of
gene. However, members
red algae contain a single conventional cox2
of at least three genetic lineages lack cox2
is the Apicomplexa (10
). We identified
the nuclear cox2a
genes of the Api-
cDNAs from Toxoplasma
complexa indicate a green algal endosymbiont
guminous plants express full-length COXII
and cloned the corresponding nuclear
) from the class Chlorophyceae. This is a re-
from the nucleus (5
). Members of the algal
genes (fig. S1). We also identified nuclear
markable example of lateral gene transfer, in thata single apicomplexan cytochrome oxidase sub-unit (COXII) has been replaced by two proteins(COXIIA and COXIIB) of green algal origin.
The use of functional split genes as atypicalmolecular markers has helped to clarify the com-plex evolution of the causative agents of malariaand toxoplasmosis.
References and Notes
1. R. J. Wilson et al.
, J Mol Biol. 261
, 155 (1996).
2. S. Ko¨hler et al.
, Science 275
, 1485 (1997).
3. G. I. McFadden, R. F. Waller, Bioessays 19
, 1033 (1997).
4. N. M. Fast, J. C. Kissinger, D. S. Roos, P. J. Keeling, Mol.
Biol. Evol. 18
, 418 (2001).
5. K. L. Adams et al.
, Proc. Natl. Acad. Sci. U.S.A. 96
6. M. W. Gray, Curr. Opin. Genet. Dev. 9
, 678 (1999).
7. X. Pe´rez-Martı´nez et al.
, J. Biol. Chem. 276
8. A. M. Nedelcu, R. W. Lee, C. Lemieux, M. W. Gray, G.
Burger, Genome Res. 10
, 819 (2000).
9. Supporting online material is available on Science
10. J. E. Feagin, Int. J. Parasitol. 30
, 371 (2000).
Maximum likelihood (ML) analyses showing the position of apicomplexan parasites based on
11. Sequencing of T. parva
and P. yoelii
is carried on by
cytochrome b (CYB) and COXIIA ϩ COXIIB sequences. COXIIA and COXIIB (excluding MTS and
the Institute for Genomic Research. We thank J. M.
extensions) were fused in silico as a single polypeptide and aligned with orthodox mitochondrial
Quinn and S. Merchant for the S. obliquus
COXII sequences. Bootstrap support Ͼ50% is indicated above branches. See materials and methods
A. Go´mez-Puyou, D. W. Krogmann, and D. A. Maslov
in supporting online material (9
for critical comments. Work supported by TW01176
(NIH), HL59646 (NIH), and IN207201 (UNAM).
class Chlorophyceae also lack cox2
in the apicomplexans Plasmo-
Supporting Online Material
). Two such algae, Chlamydomonas
, P. yoelii
, Theileria annulata
sp., have two dis-
, and Eimeria tenella
tinct nuclear cox2
Several lines of evidence suggest a common
COXIIA, corresponding to the NH -terminal
ancestry for apicomplexan and green algal cox2
Instituto de Fisiologı´a Celular, Universidad Nacional
genes. Both algal and apicomplexan cox2
Auto´noma de Me´xico (UNAM), 04510 D.F., Mexico.
encodes COXIIB, corresponding to the
appear to have been split in identical locations
Department of Biochemistry and Molecular Pharma-
cology, Thomas Jefferson University, Philadelphia, PA
COOH-terminal domain (7
). COXIIA and
(fig. S1). All predicted COXIIA proteins have a
19107, USA. 3Instituto de Biologı´a, UNAM, 04510
COXIIB are imported into the mitochondrion
125– to 170 –amino acid NH -terminal exten-
D.F., Mexico. 4Instituto de Investigaciones Biome´dicas,
). A truncated cox2
in the mtDNA of the
sion that is a cleavable mitochondrial targeting
chlorophyte alga Scenedesmus obliquus
sequence in algal COXIIA (7
). COXIIB proteins
*To whom correspondence should be addressed. E-
been recognized as a cox2a
have shorter NH -terminal extensions (43 to 60
www.sciencemag.org SCIENCE VOL 298 13 DECEMBER 2002
Leticia Esperanza Medina Esparza Lugar y fecha de nacimiento: Aguascalientes, Ags. Domicilio: Teléfono: PERFIL PROFESIONAL Profesión: (1979-1984) Universidad Autónoma de Ags. Cédula profesional: Maestría: (2001-2003) Universidad Autónoma de Ags. Cédula de maestría: Doctorado: Cedula de doctorado: Antigüedad en el trab
Health management practices for cage aquaculture in Asia - a key component for sustainability Zilong Tan1, Cedric Komar1 and William J. Enright2 1Intervet Norbio Singapore Pte. Ltd., 1 Perahu Road, Singapore 718847 2Intervet International B.V., P.O. Box 31, 5830 AA Boxmeer, The Netherlands ABSTRACT The intensification of aquaculture and globalization of the seafood trade have l